Means for operating hydraulic pullback presses



Sept. 18, 1923.

W. F. MAYER MEANS FOR OPERATING HYDRAULIQ PULLBACK PRESSES z Sheets-She et 1 Filed Nov. 12

INVEN TOR.

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Sew. 18, 1192s. M M W. F. MAYER MEANS FOR OPERATING HYDRAULIC PULLBACK PRESSES Filed Nov. 12, 1919 2 S11eets=$heet 3 gnvenkw Mir/mar j? Patented Sept. 18, 1923.

T ATES mute WALDEMAR F. MAYER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOB TO TAYLOR- WHARTON-IRON AND STEEL COMPANY, OF HIGH BRIDGE, NEW JEIEY, A COB.-

PORATION' OF NEW JERSEY.

Application filed November 12, 1919. Serial No. 387,426.

To all whom it may concern:

Be it known that I, WALDEMAR F. MAYER, a citizen of Switzerland, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Im rovements in Means for Operating Hydrau 1c Pullback Presses, of which the following is a specification.

This invention relates to means for operating hydraulic pull-back presses and in providing a positive control, whereby to obtain any predetermined operating conditions through the governing operation of a single lever.

The invention is designed for application to hydraulic pull back presses, whether Vertical or horizontal, wherein, through the single lever control, there can be obtained any desired pull-back speed, from zero to maximum; any desired stop position of the press; a proper holding down of the ram on the work piece, without crushing pressure;

and any work stroke, from zero to maxi mum.

In the drawings Fig. 1 is a view in elevation, partly in section, illustrating the invention, and showing the control lever in position to insure a work stroke of the ram.

Fig. 2 is a detail view, showing the lever in the position to insure a hold down relation of the ram.

Fig. 3 is a similar view, showing the valve in the position to cause a' pull back movement of the ram.

Fig. 4 is a similar view, showing the valve in the position to stop the ram.

Fig. 5 is a detail view illustrating the relief valve.

Fig. 6 is a sectional view of a well known type of variable delivery reversible flow pump.

The present invention is here shown as applied to a hydraulic press, comprising a supporting frame 1, including columns supporting a cylinder 2, in which is arranged a ram 3, carrying a ram plate 4. The ends of the ram plate are provided with rods 5, having pistons 6, operating in pull-back cylinders 7.

The power for the press is provided by a variable delivery and reversible flow pump 8, mounted beyond the press, and driven in any suitable manner, as by an electric motor 9. The pump 8 is of a type well known in .the art, and while shown conventionally in Fig. 6 of the drawings, needs no detailed description, forms no material part of the he bed late supporting the pump and motor is ormed to provide a reservoir 10, and arranged above the pump is a pressure tank 11, having conduits 12 and 13 extending therethrough. These conduits connect at the lower ends with the pump channels 12 and 13 respectively, whi e at. the upper ends the conduit 12 connects with the ram-cylinder through a pipe 14, the conduit 13 connecting with the pull-back cylinders through a pipe 15.

he tank 11 is formed with a transverse valve passage 16, opening through the conduits 12 and 13, this passage being open to the interior of the tank at such conduits 12 and 13, so that under proper valve control, the-ports 17 thus provided may be opened to the'tank fluid and pressure. A valve rod 18 is mounted for movement in the valve passage,- and is provided with valves 19 and 20, arranged to govern the respecresent invention, and is not claimed herein.

tive ports 17. The respective conduits 12 and 13 are enlarged in line with the valve positions therein, as at 21, so that the valves cannot entirely close the conduits under any conditions of operation, thereby providing by-passes around the valves.

The valves 19 and 20 are so arranged on the valve rod, as to prevent simultaneous closing of the ports 1.7 in any position of the valve rod, hence one or the other of the conduits is always open to the tank 11.

;The tank 11 is provided with a safety valve, as it is desired that a constant predetermined pressure be maintained in the tank. This valve is shown more particularly in Fig. 5, and comprises a casing 22, having a discharge opening 23, and in which is slidably mounted a valve rod 24, carrying 'at its lower-end an operating valve 25, normally closing the alr-escape vent of the tank. A ring 26, bearing partly upon the valve 25 and partly upon the adjacent surface of the tank, is subjected to a pressure spring 27, bearing between the, top of the casing and the ring. This spring is set for a predetermined pressure, to thereby maintain a constant pressure limit in the tank. Above the casing 22, there is arranged about the valve rod 24, an extension spring 28, between the top of the casing and a stop 29 on the valve rod. The spring 28-is weaker than the spring 27 and serves to Support the valve. p

The desired pressure is introduced into the tank 11, through an auxiliary pump 30, driven preferably from the drive shaft of the pump 8, as by a chain and sprocket connection 31. Pump 30 is of ordinary rotary single delivery type, and no detailed showing or description of such pump is deemed necessary herein. The auxiliary pump is open to the reservoir 10', and has a pipe connection 32 with the tank 11.

A manually operable lever 33 is connected with the valve rod 18, to simultaneously opcrate the valves 19 and 20. This control lever is operatively connected at the lower end with the means 34 for changing the fluid delivery of the means with the pilot valve 35 thereof, the latter 'servin as a floating fulcrum forthe lever. The elivery change means ''for the pump 8 will therefore be governed in accordance with the movement of the lever, that is with the operation of valves 19 and The auxiliary pump 30 pumps the fluid from the reservoir 10 into the tank 11, until the level of the fluid in the reservoir is below the intake of the pump, when the pump, in continued operation, delivers air under pressure to the tank. This operation places the fluid in the tank 11 under a predetermined pressure, limited by the set of the safety valve 22.

With the control lever 33 in the position shown in Fig. 3 of the drawings, the im-' proved means is arranged for the pull-back operation. The motive fluid from the pum 8 may then be delivered through the conduit 13 to the pull-back cylinders 7, the valves 20 and 19 bein in the relative-positions to close the con nit 13 against the tank 11, and to open the conduit 12 thereto. The fluid forced from the ram cylinder in the pullback operation will then be discharged part1 to the pump 8 and artly to the tank 11. y moving thecontro l lever 33 toward -the left,'the' pump delivery will gradually d1minish,.as the change control means of the pump, as 34,'is moved toward the right. The pul -back speed will. correspondingly lower, until the parts reach the positions shown in Fig. 2, when" the pump will be at zero delivery. With the pump delivery at zero, the ram will ofcourse stop, this zero dellve? position of the pump being provlded or in the position of the control lever 33,- as immediately above described. It will be noted that in'the described position the valve 1s .so arranged that theram will be moved on the idle downward stroke on further operatlon of the control lever 33 to pump 8, and above such.

permit a fluiddelivery from thepump. Notwithstanding this osition of the valves, however, the ram w1ll not be moved as long as the pump delivery is at zero. The pressure fluid from the tank that is the auxilia pump is applied to the ram and tothe pul back cylinder, but due to the larger area of the ram, the latter will pressure until it finally seats on thelwork piece with that light pressure determined by the set of the safety valve. The main pump will during this conditionbe at zero delive position, or it can circulate the fluid at m erate speed, by passing around the valves as previously explained. In the operation of. the control lever farther toward the left, until the position inFig. 1 is reached, the valve 19 will close the 'ram cylinder against the auxiliary pump pressure, and the press will operate at the full pressureof the pump 8.

Having thus described the invention, is claimed as new, is

1. In a means for operating hydraulic pull-back presses, a main pressure pump, an auxiliary pressure pump, and a single control lever to simultaneously set the main pum at zero delivery and open the ram and pullack cylinders to the pressure of the auxiliarv pump.

what

2. In a means for operating hydraulic pull-back presses, a main pressure pump, a constant-pressure tank, and a valve for simultaneously opening the'pull-back cylinders to the mam pressure pum and opening 'to the ram and pull-back cylinders, valvecontrolled communications between said conduits and the auxiliary pump, and .a singlelever to simultaneously control the main pump delivery and said valve-controlled communications.

5. In a means for operatin hydraulic pull-back presses, a variable de ivery main ressure-pump, a tank,"means 'for maintainmg a predetermined pressure in said tank, conduits .from. the main pump leadin through the tank'and to the ram and pul back cylinders, said conduits being formed with openings within the tank, valves for said openmgs, and a single lever to operate from the pump and move underf' g'thi's .1

' meeeoe said valves and simultaneously control the the ram and pull-back eylinders, valves for delivery of the main pump.

governing communication between said con- 10 6. In a, means for' operating hydraulic duits and said tank, and means for operating pull-back presses, a variable delivery main said valves simultaneously with the control 5 gressure pump, a tank, an auxiliary pump of the main pump deliver or maintaining a pressure in said tank, a In testimony whereof aflix my signasafety valve for limiting the pressure of the ture.

main tank, conduits from the main pump WALDEMAR F. MAYER. 

